1. Field of the Invention
The invention relates to a catheter set for continuous spinal anaesthesia.
2. Description of Related Art:
In continuous spinal anaesthesia, a catheter of small diameter is introduced into the area of the spine. However, problems may arise due to puncturing of the dura. In order to minimize damage of the dura and the postspinal headaches resulting therefrom, catheters with a minimum outer diameter have been used. On the other hand, up to the present, puncturing the dura has required the use of a puncture cannula through which a thin catheter is subsequently advanced, whereupon the puncture cannula is removed. Since the hole in the dura caused by the puncture cannula is larger than the diameter of the catheter, liquor flows past the catheter through the hole in the dura. This results in a high loss of liquor with possible accompanying post-spinal headaches.
German Utility Mode 88 11 408 U1 (U S. Pat. application Ser. No. 07/390,608), now U.S. Pat. No. 4,994,036 describes a catheter device for spinal anaesthesia which includes an epidural cannula that is advanced up to the dura. A spinal cannula that is longer than the epidural cannula may be inserted into the epidural cannula, the leading end of the spinal cannula carrying a tip for puncturing the dura. First, a mandrin is introduced into the spinal cannula over which the catheter is subsequently advanced after the removal of the spinal cannula according to the Seldinger-method. The diameter of the catheter is substantially the same as that of the resulting hole in the dura, so that the size of the hole in the dura is limited to a minimum. However, the catheter device described above requires a relatively complicated method of insertion.
It is an object of the present invention to provide a catheter set which can be handled easily and which reduces the possible damage to the dura to a minimum.